Due to people’s increasing dependence on social networks,it is essential to develop a consensus model considering not only their own factors but also the interaction between people.Both external trust relationship am...Due to people’s increasing dependence on social networks,it is essential to develop a consensus model considering not only their own factors but also the interaction between people.Both external trust relationship among experts and the internal reliability of experts are important factors in decision-making.This paper focuses on improving the scientificity and effectiveness of decision-making and presents a consensus model combining trust relationship among experts and expert reliability in social network group decision-making(SN-GDM).A concept named matching degree is proposed to measure expert reliability.Meanwhile,linguistic information is applied to manage the imprecise and vague information.Matching degree is expressed by a 2-tuple linguistic model,and experts’preferences are measured by a probabilistic linguistic term set(PLTS).Subsequently,a hybrid weight is explored to weigh experts’importance in a group.Then a consensus measure is introduced and a feedback mechanism is developed to produce some personalized recommendations with higher group consensus.Finally,a comparative example is provided to prove the scientificity and effectiveness of the proposed consensus model.展开更多
A new synchronization technique of inner and outer couplings is proposed in this work to investigate the synchro- nization of network group. Some Haken-Lorenz lasers with chaos behaviors are taken as the nodes to cons...A new synchronization technique of inner and outer couplings is proposed in this work to investigate the synchro- nization of network group. Some Haken-Lorenz lasers with chaos behaviors are taken as the nodes to construct a few nearest neighbor complex networks and those sub-networks are also connected to form a network group. The effective node controllers are designed based on Lyapunov function and the complete synchronization among the sub-networks is realized perfectly under inner and outer couplings. The work is of potential applications in the cooperation output of lasers and the communication network.展开更多
The cascading failure often occurs in real networks. It is significant to analyze the cascading failure in the complex network research. The dependency relation can change over time. Therefore, in this study, we inves...The cascading failure often occurs in real networks. It is significant to analyze the cascading failure in the complex network research. The dependency relation can change over time. Therefore, in this study, we investigate the cascading fail- ure in multilayer networks with dynamic dependency groups. We construct a model considering the recovery mechanism. In our model, two effects between layers are defined. Under Effect 1, the dependent nodes in other layers will be disabled as long as one node does not belong to the largest connected component in one layer. Under Effect 2, the dependent nodes in other layers will recover when one node belongs to the largest connected component. The theoretical solution of the largest component is deduced and the simulation results verify our theoretical solution. In the simulation, we analyze the influence factors of the network robustness, including the fraction of dependent nodes and the group size, in our model. It shows that increasing the fraction of dependent nodes and the group size will enhance the network robustness under Effect 1. On the contrary, these will reduce the network robustness under Effect 2. Meanwhile, we find that the tightness of the network connection will affect the robustness of networks. Furthermore, setting the average degree of network as 8 is enough to keep the network robust.展开更多
With the quick growth of sharing economy, service sharing becomes a popular phenomenon in daily lives. However, some service providers give exaggerated information about their services on the Peer-to-Peer（P2 P） serv...With the quick growth of sharing economy, service sharing becomes a popular phenomenon in daily lives. However, some service providers give exaggerated information about their services on the Peer-to-Peer（P2 P） service sharing platforms to get more profits. How to identify a reliable service provider becomes a difficult challenge for users. In this paper, we propose a trustworthy group trust metric for P2 P service sharing（TMPSS） economy based on personal social network（PSN） of users. Deriving from Advogato group trust metric, it considers factors such as social circle similarity, preference similarity, interaction degree, ranks the reliable nodes in a target user＇s PSN, outputs an ordered set of reliable nodes, and prevents unreliable nodes from access PSN of honest users. Experimental results show that TMPSS has advantages over existing representative methods because it finds more reliable nodes, and counts against malicious nodes＇ attacks more effectively, and it is suitable for mobile transaction circumstances.展开更多
Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and ...Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and puts forward the educational strategies to solve college students’network mass incidents:(1)Adhere to humanism and take appeals as the center;(2)To improve the campus network public opinion guidance mechanism under the guidance of relevant social cognition theories;(3)Strengthen communication and improve communication skills;(4)Promote information disclosure and transparency,and eliminate uncertainty and ambiguity.展开更多
Clarifying the evolution structure of public opinion induced and spread by fragmentation in college students’ network circle group is the key to understanding college students’ online social psychological demands, g...Clarifying the evolution structure of public opinion induced and spread by fragmentation in college students’ network circle group is the key to understanding college students’ online social psychological demands, grasping the development trend of public opinion, and designing targeted public opinion governance strategies. On the basis of identifying the key variables in the process of public opinion communication, DEMATEL-ISM model is used to explore the attribute positioning, relative importance level and hierarchical association mechanism of ante-variable and result variable, and then the governance strategies for fragment disordering public opinion in network circle groups of college students is designed. According to the study, exogenous stimuli, the uniqueness of discourse system, the number of spectacular texts and micro-narrative mode constituted the deep-rooted causes of fragment disordering public opinion. The unique situational and information attributes of network circle groups often become an important “booster” of disordered public opinion. The topic deviation is often accompanied with the formation of negative emotions. The corresponding public opinion governance strategies are sought from the aspects of shaping the network environment, adjusting the operation mechanism of the network circle group, improving the efficiency of using fragmented information, and optimizing the human resources of colleges.展开更多
Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and ...Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and puts forward the educational strategies to solve college students’network mass incidents:No.1.Adhere to humanism and take appeals as the center;No.2.To improve the campus network public opinion guidance mechanism under the guidance of relevant social cognition theories;No.3.Strengthen communication and improve communication skills;No.4.Promote information disclosure and transparency,and eliminate uncertainty and ambiguity.展开更多
With the popularity of wireless networks and the prevalence of personal mobile computing devices, understanding the characteristic of wireless network users is of great significance to the network performance. In this...With the popularity of wireless networks and the prevalence of personal mobile computing devices, understanding the characteristic of wireless network users is of great significance to the network performance. In this study, system logs from two universities, Dartmouth College and Shanghai Jiao Tong University(SJTU), were mined and analyzed. Every user's log was represented by a user profile. A novel weighted social similarity was proposed to quantify the resemblance of users considering influence of location visits. Based on the similarity, an unsupervised learning method was applied to cluster users. Though environment parameters are different, two universities both form many social groups with Pareto distribution of similarity and exponential distribution of group sizes. These findings are very important to the research of wireless network and social network .展开更多
ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced an agreement with Westlink part of the Finish telecommunications group Finnet, to supply a unified multi-serv...ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced an agreement with Westlink part of the Finish telecommunications group Finnet, to supply a unified multi-service metro bearer solution on February 18, 2010.展开更多
Peer-to-Peer (P2P) networks are highly dynamic systems which are very popular for content distribution in the Internet. A single peer remains in the system for an unpredictable amount of time, and the rate in which pe...Peer-to-Peer (P2P) networks are highly dynamic systems which are very popular for content distribution in the Internet. A single peer remains in the system for an unpredictable amount of time, and the rate in which peers enter and leave the system, i.e. the churn, is often high. A user that is obtaining content from a selected peer is frequently informed that particular peer is not available anymore, and is asked to select another peer, or will have another peer assigned, often without enough checks to confirm that the content provided by the new peer presents the same quality of the previous peer. In this work we present a strategy based on group communication for transparent and robust content access in P2P networks. Instead of accessing a single peer for obtaining the desired content, a user request is received and processed by a group of peers. This group of peers, called PCG (Peer Content Group) provides reliable content access in sense that even as members of the group crash or leave the system, users continue to receive the content if at least one group member remains fault-free. Each PCG member is capable of independently serving the request. A PCG is transparent to the user, as the group interface is identical to the interface provided by a single peer. A group member is elected to serve each request. A fault monitoring component allows the detection of member crashes. If the peer is serving request crashes, another group member is elected to continue providing the service. The PCG and a P2P file sharing applications were implemented in the JXTA platform. Evaluation results are presented showing the latency of group operations and system components.展开更多
27 August 2012--ZTE Corporation has signed a deal on a packet-switched core network （CN） for KPN Group Belgium （KPNGB）. KPNGB will deploy ZTE＇s packet-switched CN equipment, which supports unified radio access. T...27 August 2012--ZTE Corporation has signed a deal on a packet-switched core network （CN） for KPN Group Belgium （KPNGB）. KPNGB will deploy ZTE＇s packet-switched CN equipment, which supports unified radio access. The contract is the second of its kind between ZTE and KPNfollows from a construction project with KPN Germany （E-Plus） that was completed in September 2010.展开更多
Traditional tracking algorithms based on static sensors have several problems. First, the targets only occur in a part of the interested area; however, a large number of static sensors are distributed in the area to g...Traditional tracking algorithms based on static sensors have several problems. First, the targets only occur in a part of the interested area; however, a large number of static sensors are distributed in the area to guarantee entire coverage, which leads to wastage of sensor resources. Second, many static sensors have to remain in active mode to track the targets, which causes an increase of energy consumption. To solve these problems, a target group tracking algorithm based on a hybrid sensor network is proposed in this paper, which includes static sensors and mobile sensors. First, an estimation algorithm is proposed to estimate the objective region by static sensors, which work in low-power sensing mode. Second, a movement algorithm based on sliding windows is proposed for mobile sensors to obtain the destinations. Simulation results show that this algorithm can reduce the number of mobile sensors participating in the tracking task and prolong the network lifetime.展开更多
In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it i...In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it is not worth consuming scarce resources of sensors in computing the trajectory of each single target. Hence, in this paper, the problem is modeled as tracking a geographical continuous region covered by all targets. A tracking algorithm is proposed to estimate the region covered by the target group in each sampling period. Based on the locations of sensors and the azimuthal angle of arrival （AOA） information, the estimated region covering all the group members is obtained. Algorithm analysis provides the fundamental limits to the accuracy of localizing a target group. Simulation results show that the proposed algorithm is superior to the existing hull algorithm due to the reduction in estimation error, which is between 10% and 40% of the hull algorithm, with a similar density of sensors. And when the density of sensors increases, the localization accuracy of the proposed algorithm improves dramatically.展开更多
A new concept, the generalized inverse group (GIG) of signal, is firstly proposed and its properties, leaking coefficients and implementation with neural networks are presented. Theoretical analysis and computational ...A new concept, the generalized inverse group (GIG) of signal, is firstly proposed and its properties, leaking coefficients and implementation with neural networks are presented. Theoretical analysis and computational simulation have shown that (1) there is a group of finite length of generalized inverse signals for any given finite signal, which forms the GIG; (2) each inverse group has different leaking coefficients, thus different abnormal states; (3) each GIG can be implemented by a grouped and improved single-layer perceptron which appears with fast convergence. When used in deconvolution, the proposed GIG can form a new parallel finite length of filtering deconvolution method. On off-line processing, the computational time is reduced to O(N) from O(N2). And the less the leaking coefficient is, the more reliable the deconvolution will be.展开更多
The regular small-world network, which contains the properties of small-world network and regular network, has recently received substantial attention and has been applied in researches on 2-person games. However, it ...The regular small-world network, which contains the properties of small-world network and regular network, has recently received substantial attention and has been applied in researches on 2-person games. However, it is a common phenomenon that cooperation always appears as a group behavior. In order to investigate the mechanism of group cooperation, we propose an evolutionary multi-person game model on a regular small-world network based on public goods game theory. Then, to make a comparison of frequency of cooperation among different networks, we carry out simulations on three kinds of networks with the same configuration of average degree： the square lattice, regular small-world network and random regular network. The results of simulation show that the group cooperation will emerge among these three networks when the enhancement factor r exceeds a threshold. Furthermore, time required for full cooperation on regular small-world network is slightly longer than the other networks, which indicates that the compact interactions and random interactions will promote cooperation, while the longer-range links are the obstacles in the emergence of cooperation. In addition, the cooperation would be promoted further by enhancing the random interactions on regular small-world network.展开更多
This paper addresses an interesting security problem in wireless ad hoc networks: the dynamic group key agreement key establishment. For secure group communication in an ad hoc network, a group key shared by all group...This paper addresses an interesting security problem in wireless ad hoc networks: the dynamic group key agreement key establishment. For secure group communication in an ad hoc network, a group key shared by all group members is required. This group key should be updated when there are membership changes (when the new member joins or current member leaves) in the group. In this paper, we propose a novel, secure, scalable and efficient region-based group key agreement protocol for ad hoc networks. This is implemented by a two-level structure and a new scheme of group key update. The idea is to divide the group into subgroups, each maintaining its subgroup keys using group elliptic curve diffie-hellman (GECDH) Protocol and links with other subgroups in a tree structure using tree-based group elliptic curve diffie-hellman (TGECDH) protocol. By introducing region-based approach, messages and key updates will be limited within subgroup and outer group;hence computation load is distributed to many hosts. Both theoretical analysis and experimental results show that this Region-based key agreement protocol performs well for the key establishment problem in ad hoc network in terms of memory cost, computation cost and communication cost.展开更多
基金the National Natural Science Foundation of China(71871121).
文摘Due to people’s increasing dependence on social networks,it is essential to develop a consensus model considering not only their own factors but also the interaction between people.Both external trust relationship among experts and the internal reliability of experts are important factors in decision-making.This paper focuses on improving the scientificity and effectiveness of decision-making and presents a consensus model combining trust relationship among experts and expert reliability in social network group decision-making(SN-GDM).A concept named matching degree is proposed to measure expert reliability.Meanwhile,linguistic information is applied to manage the imprecise and vague information.Matching degree is expressed by a 2-tuple linguistic model,and experts’preferences are measured by a probabilistic linguistic term set(PLTS).Subsequently,a hybrid weight is explored to weigh experts’importance in a group.Then a consensus measure is introduced and a feedback mechanism is developed to produce some personalized recommendations with higher group consensus.Finally,a comparative example is provided to prove the scientificity and effectiveness of the proposed consensus model.
基金Project supported by the National Natural Science Foundation of China(Grant No.11004092)the Natural Science Foundation of Liaoning Province,China(Grant Nos.2015020079 and 201602455)the Foundation of Education Department of Liaoning Province,China(Grant No.L201683665)
文摘A new synchronization technique of inner and outer couplings is proposed in this work to investigate the synchro- nization of network group. Some Haken-Lorenz lasers with chaos behaviors are taken as the nodes to construct a few nearest neighbor complex networks and those sub-networks are also connected to form a network group. The effective node controllers are designed based on Lyapunov function and the complete synchronization among the sub-networks is realized perfectly under inner and outer couplings. The work is of potential applications in the cooperation output of lasers and the communication network.
基金Project supported by the National Natural Science Foundation of China(Grant No.61601053)
文摘The cascading failure often occurs in real networks. It is significant to analyze the cascading failure in the complex network research. The dependency relation can change over time. Therefore, in this study, we investigate the cascading fail- ure in multilayer networks with dynamic dependency groups. We construct a model considering the recovery mechanism. In our model, two effects between layers are defined. Under Effect 1, the dependent nodes in other layers will be disabled as long as one node does not belong to the largest connected component in one layer. Under Effect 2, the dependent nodes in other layers will recover when one node belongs to the largest connected component. The theoretical solution of the largest component is deduced and the simulation results verify our theoretical solution. In the simulation, we analyze the influence factors of the network robustness, including the fraction of dependent nodes and the group size, in our model. It shows that increasing the fraction of dependent nodes and the group size will enhance the network robustness under Effect 1. On the contrary, these will reduce the network robustness under Effect 2. Meanwhile, we find that the tightness of the network connection will affect the robustness of networks. Furthermore, setting the average degree of network as 8 is enough to keep the network robust.
基金Supported by the National Social Science Foundation of China(17BGL201)
文摘With the quick growth of sharing economy, service sharing becomes a popular phenomenon in daily lives. However, some service providers give exaggerated information about their services on the Peer-to-Peer（P2 P） service sharing platforms to get more profits. How to identify a reliable service provider becomes a difficult challenge for users. In this paper, we propose a trustworthy group trust metric for P2 P service sharing（TMPSS） economy based on personal social network（PSN） of users. Deriving from Advogato group trust metric, it considers factors such as social circle similarity, preference similarity, interaction degree, ranks the reliable nodes in a target user＇s PSN, outputs an ordered set of reliable nodes, and prevents unreliable nodes from access PSN of honest users. Experimental results show that TMPSS has advantages over existing representative methods because it finds more reliable nodes, and counts against malicious nodes＇ attacks more effectively, and it is suitable for mobile transaction circumstances.
文摘Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and puts forward the educational strategies to solve college students’network mass incidents:(1)Adhere to humanism and take appeals as the center;(2)To improve the campus network public opinion guidance mechanism under the guidance of relevant social cognition theories;(3)Strengthen communication and improve communication skills;(4)Promote information disclosure and transparency,and eliminate uncertainty and ambiguity.
文摘Clarifying the evolution structure of public opinion induced and spread by fragmentation in college students’ network circle group is the key to understanding college students’ online social psychological demands, grasping the development trend of public opinion, and designing targeted public opinion governance strategies. On the basis of identifying the key variables in the process of public opinion communication, DEMATEL-ISM model is used to explore the attribute positioning, relative importance level and hierarchical association mechanism of ante-variable and result variable, and then the governance strategies for fragment disordering public opinion in network circle groups of college students is designed. According to the study, exogenous stimuli, the uniqueness of discourse system, the number of spectacular texts and micro-narrative mode constituted the deep-rooted causes of fragment disordering public opinion. The unique situational and information attributes of network circle groups often become an important “booster” of disordered public opinion. The topic deviation is often accompanied with the formation of negative emotions. The corresponding public opinion governance strategies are sought from the aspects of shaping the network environment, adjusting the operation mechanism of the network circle group, improving the efficiency of using fragmented information, and optimizing the human resources of colleges.
文摘Based on the perspective of psychology,this paper analyzes the causes and characteristics of college students’network mass incidents,explores the psychological factors of college students’network mass incidents,and puts forward the educational strategies to solve college students’network mass incidents:No.1.Adhere to humanism and take appeals as the center;No.2.To improve the campus network public opinion guidance mechanism under the guidance of relevant social cognition theories;No.3.Strengthen communication and improve communication skills;No.4.Promote information disclosure and transparency,and eliminate uncertainty and ambiguity.
基金National Natural Science Foundation of China(No. 60970106)National High Technology Research and Development Program of China( No. 2011AA010500)
文摘With the popularity of wireless networks and the prevalence of personal mobile computing devices, understanding the characteristic of wireless network users is of great significance to the network performance. In this study, system logs from two universities, Dartmouth College and Shanghai Jiao Tong University(SJTU), were mined and analyzed. Every user's log was represented by a user profile. A novel weighted social similarity was proposed to quantify the resemblance of users considering influence of location visits. Based on the similarity, an unsupervised learning method was applied to cluster users. Though environment parameters are different, two universities both form many social groups with Pareto distribution of similarity and exponential distribution of group sizes. These findings are very important to the research of wireless network and social network .
文摘ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced an agreement with Westlink part of the Finish telecommunications group Finnet, to supply a unified multi-service metro bearer solution on February 18, 2010.
文摘Peer-to-Peer (P2P) networks are highly dynamic systems which are very popular for content distribution in the Internet. A single peer remains in the system for an unpredictable amount of time, and the rate in which peers enter and leave the system, i.e. the churn, is often high. A user that is obtaining content from a selected peer is frequently informed that particular peer is not available anymore, and is asked to select another peer, or will have another peer assigned, often without enough checks to confirm that the content provided by the new peer presents the same quality of the previous peer. In this work we present a strategy based on group communication for transparent and robust content access in P2P networks. Instead of accessing a single peer for obtaining the desired content, a user request is received and processed by a group of peers. This group of peers, called PCG (Peer Content Group) provides reliable content access in sense that even as members of the group crash or leave the system, users continue to receive the content if at least one group member remains fault-free. Each PCG member is capable of independently serving the request. A PCG is transparent to the user, as the group interface is identical to the interface provided by a single peer. A group member is elected to serve each request. A fault monitoring component allows the detection of member crashes. If the peer is serving request crashes, another group member is elected to continue providing the service. The PCG and a P2P file sharing applications were implemented in the JXTA platform. Evaluation results are presented showing the latency of group operations and system components.
文摘27 August 2012--ZTE Corporation has signed a deal on a packet-switched core network （CN） for KPN Group Belgium （KPNGB）. KPNGB will deploy ZTE＇s packet-switched CN equipment, which supports unified radio access. The contract is the second of its kind between ZTE and KPNfollows from a construction project with KPN Germany （E-Plus） that was completed in September 2010.
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140875)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications,China(Grant No.NY213084)the National Natural Science Foundation of China(Grant No.61502243)
文摘Traditional tracking algorithms based on static sensors have several problems. First, the targets only occur in a part of the interested area; however, a large number of static sensors are distributed in the area to guarantee entire coverage, which leads to wastage of sensor resources. Second, many static sensors have to remain in active mode to track the targets, which causes an increase of energy consumption. To solve these problems, a target group tracking algorithm based on a hybrid sensor network is proposed in this paper, which includes static sensors and mobile sensors. First, an estimation algorithm is proposed to estimate the objective region by static sensors, which work in low-power sensing mode. Second, a movement algorithm based on sliding windows is proposed for mobile sensors to obtain the destinations. Simulation results show that this algorithm can reduce the number of mobile sensors participating in the tracking task and prolong the network lifetime.
基金Project supported by the State Key Program of the National Natural Science Foundation of China(Grant No.60835001)the National Natural Science Foundation of China(Grant No.61104068)the Natural Science Foundation of Jiangsu Province China(Grant No.BK2010200)
文摘In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it is not worth consuming scarce resources of sensors in computing the trajectory of each single target. Hence, in this paper, the problem is modeled as tracking a geographical continuous region covered by all targets. A tracking algorithm is proposed to estimate the region covered by the target group in each sampling period. Based on the locations of sensors and the azimuthal angle of arrival （AOA） information, the estimated region covering all the group members is obtained. Algorithm analysis provides the fundamental limits to the accuracy of localizing a target group. Simulation results show that the proposed algorithm is superior to the existing hull algorithm due to the reduction in estimation error, which is between 10% and 40% of the hull algorithm, with a similar density of sensors. And when the density of sensors increases, the localization accuracy of the proposed algorithm improves dramatically.
基金Supported partly by Natural Science Foundation of ChinaAviation Science Grant of China
文摘A new concept, the generalized inverse group (GIG) of signal, is firstly proposed and its properties, leaking coefficients and implementation with neural networks are presented. Theoretical analysis and computational simulation have shown that (1) there is a group of finite length of generalized inverse signals for any given finite signal, which forms the GIG; (2) each inverse group has different leaking coefficients, thus different abnormal states; (3) each GIG can be implemented by a grouped and improved single-layer perceptron which appears with fast convergence. When used in deconvolution, the proposed GIG can form a new parallel finite length of filtering deconvolution method. On off-line processing, the computational time is reduced to O(N) from O(N2). And the less the leaking coefficient is, the more reliable the deconvolution will be.
基金Supported by the National Natural Science Foundation of China(71601148)the National Social Science Foundation of China(14ZDA062)Humanities and Social Science Research Foundation of Ministry of Education(14JDGC012)
文摘The regular small-world network, which contains the properties of small-world network and regular network, has recently received substantial attention and has been applied in researches on 2-person games. However, it is a common phenomenon that cooperation always appears as a group behavior. In order to investigate the mechanism of group cooperation, we propose an evolutionary multi-person game model on a regular small-world network based on public goods game theory. Then, to make a comparison of frequency of cooperation among different networks, we carry out simulations on three kinds of networks with the same configuration of average degree： the square lattice, regular small-world network and random regular network. The results of simulation show that the group cooperation will emerge among these three networks when the enhancement factor r exceeds a threshold. Furthermore, time required for full cooperation on regular small-world network is slightly longer than the other networks, which indicates that the compact interactions and random interactions will promote cooperation, while the longer-range links are the obstacles in the emergence of cooperation. In addition, the cooperation would be promoted further by enhancing the random interactions on regular small-world network.
文摘This paper addresses an interesting security problem in wireless ad hoc networks: the dynamic group key agreement key establishment. For secure group communication in an ad hoc network, a group key shared by all group members is required. This group key should be updated when there are membership changes (when the new member joins or current member leaves) in the group. In this paper, we propose a novel, secure, scalable and efficient region-based group key agreement protocol for ad hoc networks. This is implemented by a two-level structure and a new scheme of group key update. The idea is to divide the group into subgroups, each maintaining its subgroup keys using group elliptic curve diffie-hellman (GECDH) Protocol and links with other subgroups in a tree structure using tree-based group elliptic curve diffie-hellman (TGECDH) protocol. By introducing region-based approach, messages and key updates will be limited within subgroup and outer group;hence computation load is distributed to many hosts. Both theoretical analysis and experimental results show that this Region-based key agreement protocol performs well for the key establishment problem in ad hoc network in terms of memory cost, computation cost and communication cost.
